A magnetic memory device has a structure which includes ferromagnetic layers separated by a non-magnetic layer. Information is stored as directions of magnetization vectors in magnetic layers. Magnetic vectors in one magnetic layer, for instance, are magnetically fixed or pinned, while the magnetization direction of the other magnetic layer is free to switch between the same and opposite directions which are called “Parallel” and “Anti-parallel” states, respectively. In response to parallel and anti-parallel states, the magnetic memory device represents two different resistances. The resistance indicates minimum and maximum values when the magnetization vectors of two magnetic layers point in substantially the same and opposite directions, respectively. Accordingly, a detection of changes in resistance allows a magnetic memory device to provide stored information.
In magnetoresistive random access memory (hereinafter referred to as “MRAM”) devices, the memory cells are programmed by magnetic fields induced by a current carrying conductor such as a copper interconnect. Typically, two interconnects are employed, with one positioned above (generally referred to as the bit line) the MRAM device and the second positioned below (generally referred to as the digit line) the MRAM device. Because the name and position of the lines may be altered in various applications, the term “conductive line or lines” will be used to generally identify either or both lines hereinafter. The purpose of the electrically conductive lines is to provide magnetic fields for programming the MRAM device.
A problem with prior semiconductor processing of conductive lines for MRAM devices is that it involves using a number of expensive and complicated vacuum deposition tools and complex processing steps which increase the cycle time and cost. For example, the preferred method of forming the conductive lines is to form copper interconnects by a damascene or inlaid process wherein the conductive line is typically covered with a flux concentrating layer. The flux concentrating layer functions to focus the magnetic field around the conductive line toward the MRAM cell or bit, and, consequently, reduces the required programming current by a factor of approximately two. However, the steps involved in forming the flux concentrating material require the use of several vacuum deposition and etching tools, as well as photolayers. For example, reactive ion etching (hereinafter referred to as “RIE”) is typically used to remove the evaporated layers from unwanted areas. Unfortunately, RIE can over-etch the layers, which can cause shorting. Also, photolayers are an expensive step in device fabrication, so the cost can be reduced by utilizing alternative techniques.
It would be highly advantageous, therefore, to remedy the foregoing and other deficiencies inherent in the prior art.